[¹⁸F]-FDG positron emission tomography—an established clinical tool opening a new window into exercise physiology

Abstract

Positron emission tomography (PET) with [(18)F]-fluorodeoxyglucose (FDG) is an established clinical tool primarily used to diagnose and evaluate disease status in patients with cancer. PET imaging using FDG can be a highly valuable tool to investigate normal human physiology by providing a noninvasive, quantitative measure of glucose uptake into various cell types. Over the past years it has also been increasingly used in exercise physiology studies to identify changes in glucose uptake, metabolism, and muscle activity during different exercise modalities. Metabolically active cells transport FDG, an (18)fluorine-labeled glucose analog tracer, from the blood into the cells where it is then phosphorylated but not further metabolized. This metabolic trapping process forms the basis of this method's use during exercise. The tracer is given to a participant during an exercise task, and the actual PET imaging is performed immediately after the exercise. Provided the uptake period is of sufficient duration, and the imaging is performed shortly after the exercise; the captured image strongly reflects the metabolic activity of the cells used during the task. When combined with repeated blood sampling to determine tracer blood concentration over time, also known as the input function, glucose uptake rate of the tissues can be quantitatively calculated. This synthesis provides an accounting of studies using FDG-PET to measure acute exercise-induced skeletal muscle activity, describes the advantages and limitations of this imaging technique, and discusses its applications to the field of exercise physiology.

Different Predictors of Right and Left Ventricular Metabolism in Healthy Middle-Aged Men

“…Except for the clamp, FDG-PET was performed similarly to FTHA-PET. As FDG is not metabolized in the body (Rudroff et al, 2015 ), no additional blood samples were needed for metabolite correction. Glucose concentrations were measured at every 5 min and the whole period was used for calculations of the final GU values.…”

Fluorine‐18‐fluoro‐2‐deoxy‐d‐glucose PET‐CT aids in detection of soft‐tissue injuries for dogs with thoracic or pelvic limb lameness

“…Positron emission tomography‐CT can diagnose soft tissue pathologies and provides objective morphological lesion localization. In humans, PET‐CT is used for the clinical investigation of exercise physiology as well as to detect various musculoskeletal pathologies . The most common way to quantify PET tracer accumulation is by standardized uptake values (SUV), the tissue activity concentration normalized by the fraction of the injected dose/unit weight .…”

FDG-PET detects nonuniform muscle activity in the lower body during human gait

“…Another advantage of the FDG‐PET method is that it allows for quantification of activity from a large number of muscles. For more detailed information about the use of FDG‐PET in the study of exercise physiology, please see a recent review by Rudroff et al…”